Compared with amorphous silicon (a-Si) thin-film transistors, low temperature poly-silicon thin film transistors (LTPS TFTs) have numerous advantages, such as high mobility which can reach approximately 10-100 cm2/Vs, lower manufacturing temperature (below 600° C.), flexible selection of substrates, and low manufacturing costs. Due to the numerous excellent characteristics, the LTPS TFTs have significant advantages in the manufacturing of flexible displays, and have become the most important material for the production of flexible displays in the industry.
At present, in the process of manufacturing the LTPS TFT on a non-flexible glass substrate, source and drain regions of the LTPS active layer need to be heavily doped through an ion implantation process in order to form good ohmic contacts between the source electrode, the drain electrode and the LTPS active layer. Therefore, the contact resistances are reduced and better TFT electrical characteristics are obtained. It should be noted that after the heavily doping process, high temperature activation (high temperature annealing) at a temperature of 600° C. or more is necessary to substantially eliminate a large number of defects caused by doping in the active layer.
However, the upper temperature limit of the current flexible process is 400° C., and thus the high temperature activation following the ion implantation process cannot be carried out. Accordingly, the flexible substrate LTPS TFT manufactured by the above-mentioned non-flexible substrate TFT manufacturing method have very poor device characteristics and the large number of defects caused by heavily doping cannot be avoided.
There is no effective technical solution for the above-mentioned technical problem in the related art.